Transition assembly and method of connecting to a heat exchanger

ABSTRACT

A transition assembly is provided for connecting a heat exchanger to an external flow path. The assembly includes a fluid connection tube and a transition tube. The ends of the fluid connection tube and the transition tube are sized such that one tube may be inserted within the other tube. A portion of the exterior tube may then be deformed to retain the interior tube. The ends may be shaped by conventional methods such as swaging.

FIELD OF THE INVENTION

This invention relates to heat exchangers, and more specifically, toimproved transition assemblies for heat exchangers; as well as methodsof making a heat exchanger and transition assembly.

BACKGROUND OF THE INVENTION

Many heat exchangers in use today, as, for example, evaporators andcondensers for stationary refrigeration systems, are based on aconstruction that includes fluid connections to external flow paths forat least one of the fluids passing through the heat exchanger, such as,for example, refrigerant. Generally, a fluid to be heated and/or cooledtravels from an external source through an external flow path to theheat exchanger. Once the fluid travels through the heat exchanger, thefluid exits the heat exchanger to another external flow path. Connectingthe external flow paths to the heat exchanger can be done by brazing ifthe flow path and heat exchanger are of materials that are easily brazedto each other, however if not, fluid connections in the form oftransition assemblies are utilized to connect the external sources tothe inlet and outlet of the heat exchanger.

Heat exchangers are oftentimes manufactured from specially selectedmaterials to increase the rate of heat transfer in the heat exchanger.However, the materials selected for the heat exchanger may not be thesame material as the external flow paths and/or transition assemblies.If different materials are selected for the components, the componentsmay expand and contract at different rates. This effect becomesespecially important during the assembly of the heat exchanger andtransition assemblies.

Specifically, the transition assemblies are generally brazed to the heatexchanger through aprocess of subjecting the components to sufficientthermodynamic conditions to melt the braze material and connect thecomponents. If the heat exchanger and transition assemblies aremanufactured from materials such as aluminum and stainless steel, thealuminum components will expand more than the stainless steelcomponents. Therefore, if the components are not properly oriented or donot have fixtures retaining the components together, they may fall apartduring the brazing process. Specifically, gravity may cause one of thecomponents to fall out of the other component if the components do nothave a correct orientation. This method also has a similar drawback inthat the brazing material may not stay in a desired location during thebrazing process if the components do not have a correct orientation.

SUMMARY OF THE INVENTION

In accordance with one form, a transition assembly for connecting a heatexchanger to an external flow path is provided. The transition assemblyincludes a fluid connection tube extending from the heat exchanger. Thefluid connection tube includes a body extending from the heat exchangerhaving a first internal cross-sectional area and an extended end havinga second internal cross-sectional area which is larger than the firstinternal cross-sectional area. The transition assembly also includes atransition tube having a transition end, a coupling end and a bodyportion extending between the transition end and the coupling end. Thebody portion has a first external cross-sectional area and thetransition end has a second external cross-sectional area which islarger than the first external cross-sectional area The transition endfits substantially within the extended end and an edge portion of theextended end is deformed to retain the transition end within theextended end.

In one form, a heat exchanger is provided. The heat exchanger includes apair of spaced, generally parallel headers, a plurality of spaced,generally parallel tubes extending between and in fluid communicationwith the interior of the headers, and a transition assembly. Thetransition assembly includes a fluid connection tube and a transitiontube where the transition tube extends from an end or side of one of theheaders. The fluid connection tube includes a body extending from theheat exchanger having a first internal cross-sectional area and anextended end having a second internal cross-sectional area which islarger than the first internal cross-sectional area. The transition tubehas a transition end, a coupling end and a body portion extendingbetween the transition end and the coupling end. The body portion has afirst external cross-sectional area and the transition end having asecond external cross-sectional area which is larger than the firstexternal cross-sectional area. The transition end fits substantiallywithin the extended end. An edge portion of the extended end is deformedto retain the transition end within the extended end.

In one form, the fluid connection tube and the transition tube arebrazed together with brazing material.

According to one form, the brazing material is located on the interiorof the fluid connection tube.

In accordance with one form, the fluid connection tube is made fromaluminum and the transition tube is made from stainless steel.

In one form, the edge portion is deformed in only one location to retainthe transition end within the extended end.

According to one form, the entire edge portion is deformed to retain thetransition end within the extended end.

In accordance with one form, the body portion has a third internalcross-sectional area and the coupling end has a fourth internalcross-sectional area which is larger than the third internalcross-sectional area.

According to one form, the cross-sectional areas are circular.

In one form, a method manufacturing a transition assembly for connectinga heat exchanger to an external flow path is provided. The assemblyincludes a fluid connection tube and a transition tube. The fluidconnection tube includes a body and an extended end. The transition tubehas a transition end, a coupling end and a body portion extendingbetween the transition end and the coupling end. The method includingthe steps of:

inserting the transition end within the extended end of the fluidconnection tube such that the transition end is substantially enclosedwithin the extended end;

deforming an edge of the extended end to retain the transition endwithin the extended end; and

brazing the assembly to create a substantially fluid tight connectionbetween the fluid connection tube and the transition tube.

In one form, the method further includes the step of inserting a brazingmaterial within the extended end of the fluid connection tube prior toinserting the transition end.

According to one form, the step of inserting a brazing material includesinserting a brazing ring sized to fit within the extended end.

In accordance with one form, the step of brazing the assembly is carriedout via controlled atmosphere brazing.

In one form, the transition tube is oriented in a downward directionrelative to a gravitational force during the step of brazing theassembly.

According to one form, the method further includes the steps ofproviding the fluid connection tube with the body having a firstinternal cross-sectional area and the extended end having a secondinternal cross-sectional area and providing the transition tube with thebody portion having a first external cross-sectional area and thetransition end having a second external cross-sectional area which islarger than the first external cross-sectional area.

In one form, the cross-sectional areas are circular.

In one form, the method further includes the step of inserting an end ofan external flow path within the coupling end of the transition tube tocreate a substantially fluid tight connection between the transitiontube and the external flow path.

Other objects, advantages, and features will become apparent from acomplete review of the entire specification, including the appendedclaims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a heat exchanger and transitionassemblies;

FIG. 2 is a cross-sectional view of a transition assembly prior todeformation;

FIG. 3 is a cross-sectional view of a transitional assembly after oneform of deformation; and

FIG. 4 is a cross-sectional view of a transitional assembly after analternative form of deformation and a connected external flow path.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described hereinafter as a condenser or anevaporator for a stationary refrigeration system. However, it should beunderstood that the invention is applicable to condensers used in othercontexts, for example, a condenser for a vehicle. The invention is alsouseful in any of the many other types of heat exchangers that utilizetransition joints or assemblies to connect the heat exchanger toexternal fluid flow paths, such as stainless steel or copper conduits.Accordingly, no limitation to any particular use is intended exceptinsofar as expressed in the appended claims.

Referring to FIG. 1, a typical heat exchanger of the type of concernincludes spaced, parallel header plates 10,12, between which a pluralityof flattened tubes 14 extend. The tubes 14 are spaced from one anotherand their ends are brazed or welded or soldered and extend throughslots, not shown, in the headers 10 and 12 so as to be in fluidcommunication with the interior of the headers 10,12. In this regard, itis to be noted that as used herein, the term “header” collectivelyrefers to the header plates 10,12, to the headers 10,12 with tankssecured thereon, or integral header and tank constructions known in theart as, for example, made by tubes or various laminating procedures.Optionally, side pieces 18,20 can flank respective sides of the heatexchanger construction and extend between the headers 10,12 and aretypically mechanically connected thereto as well as metallurgicallybonded thereto.

Between the spaced tubes 14, and between the endmost tube 14 and anadjacent one of the side plates 18,20 are conventional serpentine fins22, but could be any other suitable fin, including plate-type fins. Asis well known, the fins 22 may be formed of a variety of materials.Typical examples are aluminum, copper and brass. However, othermaterials can be used as well depending upon the desired strength andheat exchange efficiency requirements of a particular application.

In a highly preferred embodiment of the invention, all of the justdescribed components, with the possible exception of the tanks 16 whichmay be formed of plastic, are formed of aluminum or aluminum alloy andare braze clad at appropriate locations so that an entire assembly isillustrated in FIG. 1 may be placed in a brazing oven and the componentsall brazed together. In the usual case, prior to brazing, an appropriatefixture is employed to build up a sandwich made up of the tubes 14alternating with the serpentine fins 22 and capped at each end by theside plates 18 and 20. The headers 10,12 are fitted to the ends of thetubes 14 and in the usual case, the side plates 18 and 20 may bemechanically coupled to the headers 10,12 typically by bending tabs onthe side plates 18 over the corresponding ends of the headers 10,12.

The heat exchanger also includes two transition assemblies 30 and 32.The components and operation of the transition assemblies 30 and 32 canbe seen in more detail in the embodiments illustrated in FIGS. 2-4.

Specifically, referring to FIG. 2, one embodiment of the transitionassembly 30 is shown prior to deformation. The transition assembly 30includes a fluid connection tube 40 extending from the heat exchanger.The fluid connection tube 40 includes a body 42 extending from the heatexchanger having a first internal cross-sectional area, which asillustrated in FIG. 2 is based upon the inner diameter (ID1) of the body42 as the cross-section of the body 42 is circular-shaped. The fluidconnection tube 40 also includes an extended end 44 having a secondinternal cross-sectional area, which as illustrated in FIG. 2 is basedupon the inner diameter (ID2) of the extended end 44 as thecross-section of the extended end 44 is circular-shaped. The secondinternal cross-sectional area is larger than the first internalcross-sectional area, as illustrated by the larger diameter ID2.

The transition assembly 30 also includes a transition tube 50. Thetransition tube 50 includes a transition end 52, a coupling end 54 and abody portion 56 extending between the transition end 52 and the couplingend 54. The body portion 56 has a first external cross-sectional area,which as illustrated in FIG. 2 is based upon the outer diameter (OD1) ofthe body portion 56 as the cross-section of the body portion iscircular-shaped. The transition end 52 has a second externalcross-sectional area, which as illustrated in FIG. 2 is based upon theouter diameter (OD2) of the transition end 52 as the transition end 52is circular-shaped. The second external cross-sectional area is largerthan the first external cross-sectional area, as illustrated by thelarger diameter OD2.

While the above description makes reference to inner and outer diametersregarding the respective cross-sectional areas, which will often bepreferred, it should be understood that other shapes are alsocontemplated. Therefore, the cross-sectional areas are not limited tothe diameters of the respective ends. For example, the ends may take theform of ovals or other shapes and thus, the ends will not have constantdiameters, but will still have a measurable cross-sectional area for therespective pieces.

Furthermore, in one preferred embodiment, the outer diameter OD2 of thetransition end 52 is substantially the same as the internal diameter ID2such that the transition end 52 fits snugly within the extended end 44.

Regardless of the shape, the transition end 52 and the extended end 44will be sized and shaped such that the transition end 52 fitssubstantially within the extended end 44. In this position, and edgeportion 60 of the extended can be deformed to retain the transition end52 within the extended end 44. The edge portion 60 is shown in FIG. 2prior to deformation. The edge portion 60 is subsequently deformed suchthat it contacts the transition end 52 and prevents the transition tube50 from falling out of the fluid connection tube 40.

Specifically, referring to FIG. 3, the edge portion 60 may be deformedat one location 62, such as by crimping. Another method of deforming theedge portion 60 is by folding the entire edge portion 60, as illustratedin FIG. 4. However, one skilled in the art should understand that otherforms of deformation can also be utilized to retain the transition tube50 within the fluid connection tube 40.

The transition assembly 30 preferably includes brazing material toprovide a fluid tight connection between the fluid connection tube 40and the transition tube 50. The brazing material may be located on theoutside of both of these tubes 40 and 50 or in a preferred embodiment,located on the interior of the fluid connection tube 40. In a highlypreferred embodiment, as illustrated in FIG. 2, the brazing material isa brazing ring 64 located on the interior of the fluid connection tube40 and adjacent the transition tube 50. The brazing material may takemany forms known to those skilled in the art, such as, for example,Nocolok-cored braze rings.

It should be understood by those skilled in the art that the extendedend 44 and the transition end 52 maybe manufactured using conventionaltechniques. For example, one technique known in the art is calledswaging whereby the ends are bent and/or shaped using known tools andprocedures. Other suitable methods of forming the ends are alsocontemplated such as by brazing or welding different sized pieces oftubing to the respective heat exchanger and transition tubes. It shouldalso be understood that the coupling end 54 of the transition tube 50may also be shaped similarly to the other ends, such as illustrated inFIG. 3. However, the coupling end 54 need not take this form.

The coupling end 54 is utilized to connect the transition assembly to anexternal flow path 70, as illustrated in FIG. 4 which will typically beof the many known forms for a fluid coupling or conduit. In one form, asseen in FIG. 4, the external flow path 70 fits within the coupling end54 and may be brazed or otherwise secured thereto. Additionally, thecoupling end 54 and the external flow path 70 maybe sized and shapedjust as the extended end 44 and the transition end 52 such that thecoupling end 54 may be deformed to retain the external flow path 70within the coupling end 54 (not shown).

The fluid connection tube 40, transition tube 50 and the external flowpath 70 may all be made of conventional materials known by those skilledin the art. In one highly preferred embodiment, the fluid connectiontube 40 is aluminum, the transition tube 50 is stainless steel and theexternal flow path 70 is copper.

During the assembly, the transition end 52 is inserted within theextended end 44 of the fluid connection tube 40 such that the transitionend is substantially enclosed within the extended end 44, as illustratedin FIG. 2. The transition end 52 need not be completely within theextended end, but just far enough such that the edge portion 60 maybedeformed to retain the transition tube 50 within the fluid connectiontube 40. The transition assembly 30 is then bonded using a suitabletechnique to create a substantially fluid tight connection between thefluid connection tube 40 and the transition tube 50.

In one form, the tubes 40,50 are brazed together. This can beaccomplished through the use of brazing material inserted within thefluid connection tube 40 or located outside of the fluid connection tube40. In one preferred embodiment, the braze ring 64 is inserted into thefluid connection tube 40 and the transition assembly 30 is subjected tosufficient thermodynamic conditions to melt the braze ring and create asubstantially fluid tight connection between the fluid connection tube40 and the transition tube 50. In one highly preferred embodiment, thebrazing is accomplished utilizing controlled atmosphere brazing.

In one embodiment, the ends 44 and 52 may be sized and shaped such thatthe transition end 52 sandwiches the braze ring 64 between thetransition end 52 and the interior of the extended end 44 prior toentering the body 42 of the fluid connection tube 40. Therefore, oncethe extended end 44 is deformed, the braze ring 64 and the transitionend will not substantially move regardless of the orientation of thetransition assembly 30 and the materials used therein.

Typically, during the brazing process, if different materials are usedfor each tube, the tubes will expand and contract at different rates andin different amounts. Therefore, it may be possible for the heatexchanger end to expand more than the transition end. If the presenttransition assembly were not used, the fluid connection tube 40 andtransition tube 50 may separate. The separation may be likely in aconventional assembly wherein gravity causes the transition tube to fallout of the fluid connection tube. However, the present assembly permitsthe tube to be oriented in any manner while minimizing the likelihoodthe tubes will separate. Additionally, the transition assembly may bepreassembled prior to connection to the fluid connection tube.

For example, referring to FIG. 1, it can be seen that the transitionassemblies may have any orientation because the components of thetransition assemblies are retained in place by the structure of theassemblies themselves. Specifically, transition assembly 30 has adownward facing orientation while transition assembly 32 has a sidewaysfacing orientation. These assemblies may be brazed in this positionwithout concern for the components separating due to gravity and thermalexpansion of the components.

1. A transition assembly for connecting a heat exchanger to an externalflow path, the assembly comprising: a fluid connection tube extendingfrom the heat exchanger, the fluid connection tube including a bodyextending from the heat exchanger having a first internalcross-sectional area and an extended end having a second internalcross-sectional area which is larger than the first internalcross-sectional area; and a transition tube having a transition end, acoupling end and a body portion extending between the transition end andthe coupling end, the body portion having a first externalcross-sectional area and the transition end having a second externalcross-sectional area which is larger than the first externalcross-sectional area, the transition end fitting substantially withinthe extended end, an edge portion of the extended end being deformed toretain the transition end within the extended end.
 2. The transitionassembly of claim 1 wherein the fluid connection tube and the transitiontube are brazed together with brazing material.
 3. The transitionassembly of claim 2 wherein the brazing material is located on theinterior of the fluid connection tube.
 4. The transition assembly ofclaim 1 wherein the fluid connection tube is made from aluminum and thetransition tube is made from stainless steel.
 5. The transition assemblyof claim 1 wherein the edge portion is deformed in only one location toretain the transition end within the extended end.
 6. The transitionassembly of claim 1 wherein the entire edge portion is deformed toretain the transition end within the extended end.
 7. The transitionassembly of claim 1 wherein the body portion has a third internalcross-sectional area and the coupling end has a fourth internalcross-sectional area which is larger than the third internalcross-sectional area.
 8. The transition assembly of claim 1 wherein thecross-sectional areas are circular.
 9. A heat exchanger comprising: apair of spaced, generally parallel headers; a plurality of spaced,generally parallel tubes extending between and in fluid communicationwith the interior of the headers; and a transition assembly including afluid connection tube and a transition tube, the transition tubeextending from one of the headers, the fluid connection tube including abody extending from the heat exchanger having a first internalcross-sectional area and an extended end having a second internalcross-sectional area which is larger than the first internalcross-sectional area, the transition tube having a transition end, acoupling end and a body portion extending between the transition end andthe coupling end, the body portion having a first externalcross-sectional area and the transition end having a second externalcross-sectional area which is larger than the first externalcross-sectional area, the transition end fitting substantially withinthe extended end, an edge portion of the extended end being deformed toretain the transition end within the extended end.
 10. The heatexchanger of claim 9 wherein the fluid connection tube and thetransition tube are brazed together with brazing material.
 11. The heatexchanger of claim 10 wherein the brazing material is located on theinterior of the fluid connection tube.
 12. The heat exchanger of claim 9wherein the fluid connection tube is made from aluminum and thetransition tube is made from stainless steel.
 13. The heat exchanger ofclaim 9 wherein the edge portion is deformed in only one location toretain the transition end within the extended end.
 14. The heatexchanger of claim 9 wherein the entire edge portion is deformed toretain the transition end within the extended end.
 15. The heatexchanger of claim 9 wherein the body portion has a third internalcross-sectional area and the coupling end has a fourth internalcross-sectional area which is larger than the third internalcross-sectional area.
 16. The heat exchanger of claim 9 wherein thecross-sectional areas are circular.
 17. A method of manufacturing atransition assembly for connecting a heat exchanger to an external flowpath, the assembly including a fluid connection tube and a transitiontube, the fluid connection tube including a body and an extended end,the transition tube having a transition end, a coupling end and a bodyportion extending between the transition end and the coupling end, themethod comprising the steps of: inserting the transition end within theextended end of the fluid connection tube such that the transition endis substantially enclosed within the extended end; deforming an edge ofthe extended end to retain the transition end within the extended end;and brazing the assembly to create a substantially fluid tightconnection between the fluid connection tube and the transition tube.18. The method of claim 17 further comprising the step of inserting abrazing material within the extended end of the fluid connection tubeprior to inserting the transition end.
 19. The method of claim 18wherein the step of inserting a brazing material includes inserting abrazing ring sized to fit within the extended end.
 20. The method ofclaim 17 wherein the step of brazing the assembly is carried out viacontrolled atmosphere brazing.
 21. The method of claim 17 wherein thetransition tube is oriented in a downward direction relative to agravitational force during the step of brazing the assembly.
 22. Themethod of claim 17 further comprising the steps of providing the fluidconnection tube with the body having a first internal cross-sectionalarea and the extended end having a second internal cross-sectional areaand providing the transition tube with the body portion having a firstexternal cross-sectional area and the transition end having a secondexternal cross-sectional area which is larger than the first externalcross-sectional area.
 23. The method of claim 22 wherein thecross-sectional areas are circular.
 24. The method of claim 17 furthercomprising the step of inserting an end of an external flow path withinthe coupling end of the transition tube to create a substantially fluidtight connection between the transition tube and the external flow path.